Simple-efficient cultivation for rapeseed under UAV-sowing: Developing a high-density and high-light-efficiency population via tillage methods and seeding rates

UAV-sowing (Unmanned Aerial Vehicle-sowing) technology is an effective approach to promote yield and economic benefits in the rice-rapeseed rotation system. However, in the pursuit of maximizing annual benefits, soil tillage methods , seeding rates, planting densities, and photosynthetic efficiencies need to be optimally integrated to establish a more efficient system. Field experiments were conducted at multiple sites over several years to explore the yield performance, economic benefits, and the mechanisms underlying high productivity under different tillage patterns and seeding rates. A two-year field experiment with a split-plot experimental design was carried out at three representative sites in the Yangtze River Basin (YRB) of China: WuHan, YiChang, and XiangYang. Three planting modes, namely CK (tillage with manual sowing, general mode), N (no-tillage with UAV-sowing, potential mode), and T (tillage with UAV-sowing) were set as the main treatments, and three seeding rates S1 (3.75 kg h m −2 ), S2 (5.25 kg h m −2 ), and S3 (6.75 kg h m −2 ) served as the sub-treatments in WuHan, while only N-S3 and CK-S3 were established in Yichang and Xiangyang. The seedling rate, population density, dry matter accumulation dynamics, photosynthetic and physiological indexes, yield, and economic benefits of rapeseed under different cropping patterns were measured and compared. From all sites and years, we found that: (1) The highest yield was achieved at the seeding rate of S3 in all modes. As the seeding rate increased from S1 to S3, the yield gap between the N mode and CK as well as T gradually decreased. Moreover, the yield of N-S3 could surpass that of CK-S2 by 5.2–7.5 %, reaching a high-yield level. (2) The benefit-cost ratio (BCR) was notably higher in the N mode than in CK by 19.5 % and in T by 11.6 %. (3) The highest seedling number was observed in T-S3, but the highest seedling rate was observed in T-S1. Compared with T-S1, the seedling number in T-S2 and T-S3 increased by 7.2 % and 13.3 %, respectively. Meanwhile, the seedling rate decreased by 14.3 % and 29.5 %, respectively, while the harvest density increased by 46.4 % and 143.1 %, respectively. (4) Through the comparison of various indexes measured in different modes, it was revealed that reasonably dense planting is capable of balancing the conflict between individuals and population and maximizing the greater group productivity. (5) The economic benefits analysis and correlation network analysis indicated that the yield and planting benefits within the high-yield and high-efficiency system showed a significant positive correlation with population density as well as radiation use efficiency (RUE). Mode N combined with a large seeding rate (S3) effectively reduced planting costs, enhanced seeding quality, and boosted the population's RUE. It also balanced yield and profitability, achieving the highest BCR. These findings emphasize the potential of the no-tillage with UAV-sowing technology as a simple-efficient production technology. Furthermore, the associated technological parameters and mechanisms present extensive prospects for green agriculture . • UAV-sowing improve economic efficiency under rice-rapeseed rotation system. • No-tillage fields can also improve yield by optimizing rapeseed population. • Optimized rapeseed population enhanced the light utilization efficiency at high density.